1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus.
2. Description of the Related Art
As an electrophotographic photosensitive member to be mounted on an electrophotographic apparatus, an electrophotographic photosensitive member containing an organic photoconductive substance (charge generation substance) is commonly used. As an electrophotographic apparatus repeatedly forms an image, electric and mechanical external forces such as charging, exposing, developing, transferring and cleaning external forces are directly applied to the surface of an electrophotographic photosensitive member, and thus there is a demand for durability to such external forces. Furthermore, there is also a demand for reducing the frictional force to a contacting member (cleaning blade or the like) (lubricating properties and slipping properties) on the surface of an electrophotographic photosensitive member.
In order to solve the problem of lubricating properties, a method of adding a silicone oil such as polydimethylsiloxane to the surface layer of an electrophotographic photosensitive member has been proposed in Japanese Patent Application Laid-Open No. H07-13368. In addition, a method of using a polycarbonate resin having a siloxane structure at the end for the surface layer of an electrophotographic photosensitive member has been proposed in Japanese Patent No. 3278016. In addition, a method of using a polyester resin having a siloxane structure at the end for the surface layer has been proposed in Japanese Patent No. 3781268.
However, it has been found that if the silicone oil is contained in the surface layer of the electrophotographic photosensitive member as in Japanese Patent Application Laid-Open No. H07-13368, there may be a tendency that the surface layer is whitened to result in the reduction in sensitivity to thereby lower image density.
In addition, it has been found that if the polycarbonate resin and the polyester resin each having a siloxane structure at the end are used as in Japanese Patent No. 3278016 and Japanese Patent No. 3781268, the variation in bright portion potential due to the repeating use of the electrophotographic photosensitive member may be large as compared with the case of using a resin not having a siloxane structure.